This invention is directed to wire twisting machines and in particular to apparatus for twisting two or more electrical conductors of discrete length, which have a portion of their insulation stripped at each end, into a single cable.
Two forms of wire twisting apparatus are known in the prior art. One type of apparatus is suitable for forming twisted cables from wires of indefinite length, while the second type of prior art apparatus is designed to twist together individual wires which have portions of the insulation stripped from one or both of the ends. An example of the first type of twisted cable-forming apparatus is shown in U.S. Pat. No. 3,180,372, wherein wire to form the cable is drawn from a plurality of reels secured to and rotatable with a twister head wherein they are twisted to form the cable and from which they pass directly to a dead block take up unit supported on the frame of the apparatus. The take up unit draws the cable through the twister head and forms it into loose coils. This twisting of the wires is achieved by holding the take up unit fixed while rotating the reels and twister head with respect thereto.
The apparatus according to the '372 patent, while suitable for twisting wires into cable of an indefinite length, is unsuitable for use in twisting short pieces of wire of length up to 3 to 4 feet. Accordingly, in circumstances where individual strands of wire of a finite length are to be stripped and twisted a second form of wire twisting apparatus has been utilized. In U.S. Pat. No. 3,750,720 a wire twister is disclosed which is representative of this second type of twisting apparatus. In the apparatus according to this patent the operator has to go through a number of preliminary steps to put the apparatus in condition to receive a set of wires to be twisted together, after which each of the stripped ends has to be secured in place, the apparatus returned to an operating position, the wires twisted, and then the process repeated so as to enable the cable to be removed and the next set of wires inserted. To achieve the twisting of the wires, the first stripped ends of the wires had to be secured in a clamping device consisting of a pair of rotatable jaws and the other ends of the wires secured in fixed clips. After the wires were secured in position, the jaws were caused to rotate with respect to the clip thereby twisting the wires. As will be appreciated, since the twisting of the wires produces a cable that is shorter in length than the wires individually, the jaws are provided with a means to facilitate their axial movement with respect to the clip securing the other ends of the wires. Accordingly, the apparatus provides a very slow output rate due in particular to the number of steps required to be taken by the operator to set up and remove each pair of wires, and the structure of the apparatus as a whole is complex and costly to produce.
Accordingly, it is an object of this invention to provide a relatively simple machine for twisting a plurality of individual strands of wire, the ends of which have been stripped.
Another object of this invention is to provide an improved wire twisting machine which will twist a plurality of strands of varying gauges to produce cables of predetermined length without the need for the operator to do anything more than insert the wires into an opening.
A further object of the invention is to achieve the above-noted objects without the need for utilizing a complex and relatively expensive apparatus.
In accordance with the present invention the above and still further objects are achieved by an apparatus wherein wires of discrete length are fed into an opening in the twist die so as to be gripped in the nipped form between a power roll and a pinch roll, both of which are mounted so as to rotate about the axis of the die opening as well as their own axes, and from which the twisted cable proceeds into an air manifold where it is held in a laterally stable position within a stream of air until the entire wire comes to rest in a wire guide from which the completed cable is dropped into a storage tray.
These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, several embodiments in accordance with the present invention.